Breathing apparatus for respiration at high altitudes



"DEC. 16, 1947. MARGARlA 2,432,627

BREATHING APPARATUS FOR RESPIRATION AT HIGH ALTITUDES Filed March 18,1941 Litres Of 02 1 2 4 6 a l0 lz RoooLFo MARGAR/A fliforney PatentedDec. 16, 1947 BREATHING APPARATUS FOR RESPIRATION AT HIGH ALTITUDESRodolfo Margaria, Milan, Italy; vested in the Attorney General of theUnited States Application March 18. 1941, Serial No. 384,006 In ItalyMarch 7, 1940 3 Claims. 1

The breathing apparatus used heretofore at high altitudes and generallywhere air is rarefied are not very rational because they do not allow asufficient increase in the breathing mixture, and because not all thewhole amount of oxygen supplied is utilized for breathing.

Recently Boothby and Lovelace (see the review Aviation Medicine No. 9 ofthe ear 1938, page 1'72) have described a type of breathing mask,answering rather well to its object, but having yet-the drawback ofallowing the respiration of a part of the expired air, which should beuseful to increase the resistance to anoxaemia.

As one of the applicants has shown (R. Margaria in Giornale di MedicinaAeronautica 1939-2) it has been finally established that such a practiceinstead of being an advantage is useless and altogether harmful.

The object of the present invention is an apparatus for supplying oxygenfor breathing in rarefied air, according to which the supply of this gasto the lungs is adjusted so as to obtain the best possible utilizationof the oxygen supplied.

The apparatus is characterized by'means supplying first directly to thealveoli of lungs an amount of gas 02 pure, which in said alveoli ismixed with alreadyenriched air, driven out of the said alveoli to occupythe respiratory channels during each expiration for returning during thesubsequent inspiration in said alveoli and by means which subsequentlsupply the atmospheric air poor in oxygen to the respiratory channels,driving it out in the atmospheric air during the subsequent expiration.

This apparatus allows to supply to the lungs first a suitable amount ofpure O y and sequently, the outer atmospheric air poor in oxygen: thusthe oxygen enters entirely in the alveoli of the lungs, where it miXeswith the inspired surplus of air, whilst in the respiratory channels,where no gaseous exchanges with the blood take place there is only theouter atmospheric air, poor in oxygen.

During the subsequent expiration this poor air of the respiratorychannels is immediately driven out and at the end of the expirationthere will remain in said channels the rich air formerly contained inthe alveoli so that this air, in the subsequent inspiration, will beagain drawn into the alveoli and will therefore be utilized.

The calculations of the'amount of oxygen to be supplied, may thereforebe based on the alveolar ventilation, insteadof being based on the wholeZ lung ventilation so that there is a g a Saving in the supplied oxygen.

The invention is il'ustrated in a practical embodiment thereof in Fig.1of the accompanying drawing. while Fig, 2 shows a diagram permitting thesupplying regulation, in relation to the different altitude conditions,and consequently of air raref action.

The apparatus consists in two parts: one A of a reduced capacity, haspreferably the form of a cylinder, closed at the top" and open at thebottom base and is formed of rigid materials, for instance with metal,ebonite, synthetic resins or the like: it is divided by a diaphragm Cinto two superposed chambers A-A". The diaphragm C presents a valve Mcontrolling the passage between the two chambers A and A as will bedisclosed hereinafter.

On the lower chamber A", openat the bottom, is fitted, perfectly tight,a bag B, preferably in rubber, whilst chamber A is connected by pipes D,E which enter into tubes F, G of a rubber nosecover H, provided withfixture straps I, said cover fitting onto the nose of the operator sothat the supply of the gases for breathing is provided solely throughthe nose cavities. The mouth remains entirely free, so that the pilot orthe airplane passenger may talk, eat, vomit, without requiring anyremoval of the mask and without any interruption in the supply of theoxygen.

The chamber A of member A communicates by means of an inhalationcheck-valve M, with chamber A" and therefore with-bag B, there beingthus two chambers of a very difierent volume capacity, since normallythe volume capacity of the bag is about 1 /2 liters.

Pure oxygen flows constantly into said capacity formed by bag B and bychamber A" from a tube N traversing the wall of A" out of a bottle (notrepresented in the drawing), provided with a pressure reducing valve andwith a flux-meter (also not shown in the drawing) On the side-wall ofchamber A" is provided an inhalation valve Oallowing outside air toenter the bag B, but preventing the oxygen contained in said bag fromleaking out.

When the user commences an air inspiration, first only valve M- opens,and the oxygen contained in the bag B flows into the lungs; onlyafterwards, it can overcome the resistance of valve 0 which opens andoutside atmospheric air, poor in oxygen, is drawn in. Valve L willnormally remain closed.

In this manner the oxygen collecting in bag B enters directly in thealveoli of the lungs and will be entirely utilized, being mixed only atthe end of the inspiration and only partially with the rarefied air, sothat a smaller oxygen quantity can be supplied than in the case that themixing would be efiected and utilized forbreathing; effectively oxygenenters in all alveoli and the respiratory channels are only occupied bythe very poor atmospheric air.

In exhaling, the air passes from the nostrils to tubes FGDE into chamberA. Valve M closes and valve L opens, and out of said valve L flows thewhole air occupying the respiratory channels, then the enriched airwhich flows out of the lungs occupies the respiratory channels, In thesubsequent inspiration this formerly enriched air, returns to the lungswith a fresh quantity of oxygen, so that a new utilization takes place.

Valves L, M, O are formed with rubber or mica membranes and may hav anysuitable structure.

In order to better show the advantages of the present invention, in Fig.2 a diagram is given showing the amount (in liters, at cent. tem--perature and 760 mm. mercury pressure) of oxygen to be supplied, inrelation to the altitud in kilometers above the level of the sea, whichis the most important application for the living in aeroplanes flying athigh altitude; similar considerations could naturally be made for airrarefied for any other reason. The amount of oxygen supply to maintain ahigh partial pressure of oxygen in the alveoli, namely a pressure equalto that obtaining at sea level-varies of course with the ventilation ofthe lungs (or of the alveoli). It is well known that the latter variesin linear proportion with individual metabolism, at least up to valuesof the same which are not excessive and that each liter of expired aircorresponds to an energy consumption of about 0.25 calory (see R.Margaria Transactions of the Reale Accademia dei Lincei Series VI, vol.VII, part V, 1938 at page 859).

A man resting in a chair, consumes 1 calory per minute; when he movesnow and then the arms or the legs as a pilot does in usual practice, themetabolism or energy consumption does not exceed two calories perminute. The ventilation of the lungs, viz. the amount of air inhaled andexhaled every minute, for the case considered of an energeticconsumption of two calories per minute, will b 8 liters, as every 0.25calory consumed corresponds to 1 liter of exhaled air.

Supposing the frequency of respiration, namely the number ofinspirations per minute, to be 15, the depth of respiration will amountto 533 cubic centimeters and, supposing the clearance volume forrespiration to be 150 cubic centimeters the alveolar respiration willamount to 5.75 liters, as obtained by subtracting said clearance volume.from the breathing depth and then by multiplying the result by thebreathing frequency.

The amount of oxygen to be supplied in order that, in addition with air,it should provide such. a dose as would maintain the partial pressure ofoxygen as obtained at sea-level, is shown, for the case inconsideration, in the diagram Fig. 2.

Said diagram has been plotted, taking into consideration the increase involume of the gas due to the decrease of atmospheric pressure andconsidering also that said gas within the lungs is at 37 cent. andsaturated with Water vapour, wherein the partial pressure is 47 mm.mercury column.

'It is apparent that with the breath apparatus specified above, bothpilot and passengers of a civil aircraft, on using only 1.3 liters ofoxygen per minute, can fly up to 10,000 meters altitude, remainingexactly in the same condition, concerning respiration exchanges, as ifthey were at sea-level. If on the contrary the calculation should bebased on lung ventilation (8 liters instead of 5.75 in the above case)the amount of oxygen required in the same conditions would rise to 1.7liters.

As mentioned above, the apparatus specified is shown merely as anexample of embodiment of the invention. It may be varied in dimensions,in the shape of its various parts, provided it should achieve the methodfor supplying oxygen as claimed in the present invention.

So, for instance, pipe N supplying oxygen, might be extended furtherdownwardtowards the bottom of bag B; the expiration valve L, instead ofbeing placed sideways, might be placed in front of chamber A etc. Alsothe apparatus might be provided, with some accessory, as for instance acorrugated pipe to be inserted between part A carrying th valves and thenose attachment (or any other suitable point) thus allowing the pilotmore freedom in the movements. Also the straps for holding thenose-cover applied to the face might be of any proper shape.

What I claim is:

1. A breathing apparatus of the character described comprising a rigidchamber, a partition dividing said chamber into two compartments, aflexible lung bag connected in permanent communication with onecompartment, means for continually supplying oxygen to said bag and thecompartment in communication therewith, a nasal mask connected incommunication with the other compartment, a check valve in the partitionfor preventing flow of gas from the compartment in communication withthe nasal mask to the other compartment and permitting the reverse flow,a check valve associated with the compartment communicating with thenasal mask to enable discharge of gas from said compartment to theatmosphere and prevent inflow of air from the atmosphere, and a checkvalve associated with the compartment in communication with the bag toprevent discharge of gas from the compartment and enable the intake ofair from the atmosphere.

2. In a breathing device for supplying a mixture of air and oxygen forbreathing by a user of the device, the combination of a nasal mask; achamber communicating with said mask; a second chamber; means to supplyoxygen to said second chamber; a check valve in said first chamber,preventing ingress of air and permitting reverse flow a check valve insaid second chamber, permitting ingress of air and preventing egress ofoxygen; and a check valve connecting said chambers, permitting flow ofoxygen and air from said second chamber to said first chamber, andpreventing reverse flow.

3. In a breathing device for supplying a mixture of air and oxygen forbreathing by a user of the device, the combination of a tubular elementof rigid material, closed at one end and open at the other end; acollapsible bag of a flexible material impervious to gases, attached tosaid tubular element about said open end by a gas-tight joint; a rigiddiaphragm disposed in said tubular element transverse of thelongitudinal axis of said element intermediate its ends and dividingsaid element into two chambers, adjacent to and remote from said bag,respectively; a rigid pipe for supplying oxygen to the device, said pipepass- 5 ing through the wall of said element in a gastight joint,through said chamber adjacent said bag, and outwards from said elementthrough its open end and into said bag; the said chamber adjacent thebag being connected with the atmosphere by a port, a check-valvedisposed in said ported chamber and cooperating with said port to admitair into said chamber and prevent reverse flow; the said chamber remotefrom said bag being connected with the atmosphere by a port, a secondcheck-valve co-operating with the last mentioned port to permitdischarge of air from the last mentioned ported chamber and preventreverse flow; the diaphragm being provided with a port affordingcommunication between said two chambers; a third check-valveco-operating with the diaphragm port to permit passage of oxygen and.air from th chamber adjacent the bag to the other chamber and preventreverse flow; and a pair of pipes communicating with the chamber remotefrom the bag and connected with the nostrils of the user of the device,respectively.

RODOLFO MARGARIA.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,185,997 Heidbrink Jan. 9, 19402,228,502 Boothby Jan. 14, 1941 1,129,171 Cunningham Feb. 23, 19152,269,500 Wildhack Jan. 13, 1942 OTHER REFERENCES

